签派员在航班起飞前应该提前几小时去准备资料获取信息？

[单选题]Exports are either raw materials or manufactured goods. Raw materials are products of the land， such as cotton， timber or rubber. Some raw materials， such as iron ore， come from mines. These raw materials are often exported by the countries that produce them to other countries where they are made into manufactured goods. Some countries produce food for export， for example， meat， sugar， or cereals such as wheat and maize. These countries are agricultural countries. An agricultural country needs fertile land and a good climate. A cold， dry climate is not suitable for agriculture. A country which produces manufactured goods is known as an industrialized country. An industrialized country cannot always produce enough food for its own needs. In this case， it does not export foodstuffs. Instead it has to import them. It relies on exports of manufactured products and pays for imports with the money it earns from the exported goods. From the first sentence of the passage we can know that there are（）kinds of exports.

[问答题]“沧浪之水清兮，可以濯吾缨；沧浪之水浊兮，可以濯吾足。”出自屈原的什么作品？

[单选题]一瓶氦气和一瓶氮气它们每个分子的平均平动动能相同，而且都处于平衡态，则它们（　　）。[2013年真题]

[单选题]爆炸危险场所使用的电缆和导线的额定电压不得低于（）V。

[单选题]关于卵巢肿瘤，下述错误的是（）

[单选题]本病的最佳固定方法是（　　）。

[问答题]TDZ1A-10/25/型主断路器的隔离开关在分合闸过程中有什么的特点？

[判断题]列车进路上的无岔区段，应选用2/Q组合类型图。

[单选题]下面哪种不属于兴奋剂类毒品（）

[名词解释题]布光